The physiological blocking of pain may be accomplished by a mechanism known as presynaptic inhibition, which decreases the sensory input to the first relay neuron of the spinal cord. Medications, heat treatment, ultra sound therapy and vibration may be used to obtain pain relief. Where mechanical vibration is used to treat pain relief, the vibratory devices used are often subject to overheating from prolonged usage, or being of inadequate size for an intended target area of the body.
There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles. The main mechanoreceptors in the joints are Pacinian corpouscles and Merkel's discs. Conventional devices used by physiotherapists typically provide an electrical stimulation which just stimulates the nerve. Different joints often require different stimulating amplitude and/or frequency. In particular, frequency variations targeted for a specific mechanoreceptor type provides additional effectiveness for alleviating stiffness and pain.